How is a pregnancy due date estimated?

A common estimate counts 280 days, or 40 weeks, from the first day of the last menstrual period. If conception date is known, the estimate is about 266 days from conception.

Is this calculator a medical diagnosis?

No. It provides an estimate only. A clinician may confirm or adjust pregnancy dating using ultrasound and medical history.

Can cycle length affect the due date estimate?

Yes. LMP-based estimates often assume a 28-day cycle, so longer or shorter cycles can shift the estimated ovulation and due date.

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Pregnancy Calculator

Estimate your due date, current pregnancy week, trimester, and key milestones using LMP or conception date.

Calculation Method

First Day of Last Period

Average Cycle Length

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Enter your details to see the result panel, saved progress for logged-in users, and personalized nutrition guidance.

Pregnancy Due Date Calculator

Use this calculator to estimate your due date, pregnancy week, trimester, conception timing, and key pregnancy milestones. You can calculate from the first day of your last menstrual period or from a known conception date.

Method	Estimate	Best When
Last menstrual period	About 280 days from LMP	You know the first day of your last period.
Conception date	About 266 days from conception	You have a reliable conception or ovulation date.

How the Pregnancy Calculator Works

The calculator uses common pregnancy dating rules for estimates. LMP dating assumes a 40-week pregnancy from the first day of the last menstrual period, with cycle-length adjustment. Conception-date dating estimates 38 weeks from conception.

Confirm Dates With a Clinician

Pregnancy dating can change after ultrasound or medical review. Use this as a planning estimate, not a diagnosis.

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